Determining confining and interaction forces on dust in a 2D structure

The behavior of micron sized dust particles in complex plasmas can give insight into plasma conditions that are otherwise difficult to probe and determine. The dust particles tend to charge negatively and interact with the positive ions flowing towards a negatively charged surface, creating an ion wakefield that influences the charge and interparticle forces between dust grains. This interaction contributes to the self-assembly of the dust into ordered structures. These structures can further be influenced by changing the confining forces acting on the system. Strong horizontal confinement can be provided by the charged walls of a glass box placed on the lower electrode of a modified Gaseous Electronics Conference (GEC) cell, which allows vertical structures to form in the overlapping sheaths. Small adjustments to the system power alter the horizontal confinement causing a 1D chain to transition into two side-by-side chains (a 2D zig-zag structure). To investigate the confinement forces, a molecular dynamics simulation has been utilized to model the motion of both the ions and dust in this configuration. An iterative method is then employed to determine a position-dependent electric field that gives a minimal force-balance of the dust grains, which will lead to a stable structure.